1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a manufacturing method of an electrophotographic photosensitive member, a process cartridge and an electrophotographic apparatus each having an electrophotographic photosensitive member, and a solid solution and a manufacturing method of a solid solution.
2. Description of the Related Art
Since the oscillation wavelength of a semiconductor laser commonly used as an image exposing unit in the field of electrophotography is in the long wavelength range of 650 to 820 nm, electrophotographic photosensitive members having high sensitivity to the light in the long wavelength range are currently under development.
A phthalocyanine pigment is an effective charge generating substance having a high sensitivity for light in the long-wavelength region. In particular, oxytitanium phthalocyanine and gallium phthalocyanine have excellent sensitivity properties, and various crystal forms thereof have been reported thus far.
Although an electrophotographic photosensitive member using a phthalocyanine pigment has excellent sensitivity properties, a problem is that the generated photo carriers tend to remain in a photosensitive layer so as to act as a memory, easily causing potential variation such as ghosting.
Japanese Patent Application Laid-Open No. 2001-040237 and Japanese Patent Application Laid-Open No. H05-333575 disclose that the addition of a specific organic electron acceptor or an N-type conductive pigment during the acid pasting process of a phthalocyanine pigment has a sensitizing effect. This method, however, has causes concerns of the chemical change of an additive (an organic electron acceptor or an N-type conductive pigment), with a problem of difficulty in the transformation into a desired crystal form.
Further, Japanese Patent Application Laid-Open No. H04-351673 discloses that a mixed crystal of oxytitanyly phthalocyanine and hydroxygallium phthalocyanine is useful as a charge generating substance.
Various attempts have been made to improve electrophotographic photosensitive members as described above.
For further improvement in high-quality picture in recent years, it is desired to prevent image degradation due to ghosting in various environments.